The study uses a combination of biochemical, cytochemical and electrophysiological techniques in oder to determine biochemical mechanisms involved in the control of cochlear homeostasis and in disorders of this homeostasis caused by noise and ototoxic drugs. Adenylate cyclase is investigated in cochlear and vestibular structures as well as the influence of hormones and drugs on this enzyme. The effects of noise exposure on utilization and on lipid turnover in cochlear structures will be studied.